Recently, in the packet communication system and the mobile communication system, there is increasingly conducted data communication for mail transmission and reception, access to the internet, and Web browsing using a mobile station. To implement such data communication, for the data communication between a terminal and a Packet Data Serving Node (to be referred to as PDSN or access server hereinbelow), it is common practice to use a Point to Point Protocol (to be referred to as PPP hereinbelow) stipulated by RFC1661 (reference is to be made to, for example, 3GPP2 X.S0011-C cdma2000 Wireless IP network Standard). It is the function of the PPP to assuredly connect the apparatuses to each other to transfer an IP packet therebetween. In the mobile communication system, when a mobile station sends an IP packet to a content server as an access destination, the communication is conducted between the mobile station and the PDSN using a PPP packet created by adding a PPP header to the IP packet. The PDSN removes the PPP header from the PPP packet to restore the PPP packet to the IP packet. From the PDSN, the IP packet is routed through the IP packet communication to the content server as a transmission destination.
The basic operations using the PPP include operations for connection and disconnection between the apparatuses. In phases respectively called a link establishment phase, a user authentication phase, a network-layer protocol phase, and a link termination phase, PPP packets corresponding to the respective phases are communicated between the apparatuses to thereby implement the connection and disconnection therebetween. In this regard, the Link Control Protocol (to be referred to as LCP hereinbelow) phase is used to establish a data link after a physical line is completely connected. Also, the user authentication phase is a phase to conduct user authentication, for example, qualification or non-qualification of an access right for a connection request source. Moreover, the Network Control Protocol (to be referred to as NCP hereinbelow) is a phase, for example, to release a network using the NCP, and the link termination phase is a phase to terminate the PPP link.
In a more detailed description, the PPP includes two protocols, i.e., LCP and NCP. The LCP is a protocol to control link establishment and to control user authentication on assumption that a physical line has been connected. The NCP is a protocol has a function to conduct assignment of addresses to be used by a layer-3 protocol (network-layer protocol), and if the network layer is based on, for example, an Internet Protocol (IP), the protocol includes a function to assign an IP address.
In the conventional network connection, as stipulated by Phase Diagram in Section 3.2 of RFC1661 (The Point-to-Point Protocol), a sequential procedure is employed to conduct network connection from a terminal. The terminal issues a call to the PDSN, the link establishment processing and the authentication processing are executed by the LCP and the assignment processing of addresses to be used in the network layer is executed by the NCP to thereby completely achieve the connection to the network.
Additionally, as a technique to shorten the communication procedure, JP-A-2000-232497 has disclosed a technique in which information required in subsequent negotiation is beforehand transmitted in preceding negotiation to reduce the number of the subsequent negotiation steps to thereby shorten the connection time.